Pros
Working with a lot of like-minded outdoorsy people is a lot of fun, and learning all about the different products has been great. Training is very good, they make sure you have at least a decent knowledge of what you're selling. The connection to the Outdoor School is AWESOME.
Cons
Management is extremely pushy/aggressive about selling memberships. Many of my fellow coworkers lie to customers just so they can sell more memberships, and I constantly have customers ask me if we are on a commission-based salary because they are harassed so often (we are not). Maybe just a unique aspect to the store I work at? Also keep in mind that although REI offers great benefits, that only applies to full-time employees, and getting a full-time position is extremely competitive (you have to sell a ton of memberships regularly). You are also only given hours based on the memberships you sell, so if you don't sell many memberships, expect a 4 hour work week (I am only disgruntled about this because I had been promised 25+ hours when I was hired).